FIG. 15 is a sectional view illustrating an example of a configuration of a conventional vacuum valve. As shown in FIG. 15, in the conventional vacuum valve, Openings on both ends of an insulation vessel 601 made of, for example, ceramics, are sealed with a fixed side sealing metal fitting 602 and a movable side sealing metal fitting 603, respectively. A fixed side conductor 604 passes through the fixed side sealing metal fitting 602, and is fixed to it. A fixed side electrode 605 is fixed to one end of the fixed side conductor 604.
A movable side electrode 606 is disposed to face the fixed side electrode 605. The movable side electrode 606 is fixed to one end of a movable side conductor 607 which passes though an opening of the movable side sealing metal fitting 603, and can move along the opening. A magnetic field (vertical magnetic field) is axially generated by the fixed side electrode 605 and the movable side electrode 606.
One end of elastic bellows 608 is fixed to the intermediate part of the movable side conductor 607. The other end of the bellows 608 is fixed to the movable side sealing metal fitting 603. A cylindrical shield 609 is disposed to surround the electrodes 605, 606 and is fixed to the inside of the insulation vessel 601.
The vacuum valve configured as mentioned above is molded by insulating material, for example a resin, and an insulating part 610 is formed. A conductive part 611 is formed on the outer circumference of the insulating part 610 by application of conductive paint. The conductive paint is, for example, silver paint.
In the above-mentioned vacuum valve, when an operating mechanism not shown is driven, the movable side conductor 607 which is connected to the operating mechanism moves axially. Then, the fixed electrode 605 and the movable electrode 606 can be electrically brought into contact or out of contact with each other. When the fixed electrode 605 and the movable electrode 606 are separated from each other, an arc occurs. However, the arc is diffused throughout contact points of the electrodes 605,606 by the effect of the vertical magnetic field.